A method is proposed by which a burn-in test of a semiconductor memory having redundant word lines involves multiple selection of a real word line and a redundant word line (see, for example Japanese Patent Application Laid-Open Nos. 2000-260199 and H11-203894). In this type of testing method, the redundant word line is selected by decoding external addresses received at address terminals.
However, the external addresses are supplied to an address decoder configured to select a real word line. Accordingly, when selecting the redundant word line by using the external addresses, an unintended real word line may be selected unless the address decoder to select the real word lines is stopped. Therefore, if extra stress is applied to the real word lines resultantly, reliabilities of the semiconductor memory may possibly be deteriorated.